Magnetic control systems



Jan. 22, 1963 WAY DONG woo EI'AL 3,075,179

MAGNETIC comer. SYSTEMS Filed Dec. 2, 1953 FIG. 2 PULSE o DRIVER l0 /0/s 6 1/ /3 I5 /6 TIME TIME DELAY DELAY /NVEN RS 1776. To

WAY Dolvs Woo ROBERT D. Koo/s SM/L RUHMAN ATTORNEY 3,975,179 MAGNETECQGNTRQL YSTEM Way Dong Woo, Arlington, Rehert ll). Kodis, Roxhury,

and Snrii Ruhman, Waltham, Mass, assignors to Raytheon Company,Lexington, Mass, a corporation of Delaware Filed Dec. 2, 1%3, Ser. No.395,692 6 Saints. (Cl. Edd-$74) This invention relates to a magneticcontrol system and more particularly to systems for storing andtransferring information pulses for computer purposes. It has previouslybeen known that information could be stored in torodial magnetic coresby driving the cores into saturation. If the cores had a high magneticretentivity, the information would remain in the core as long as it isdesired, an could be read out of the core by subjecting the core to acurrent pulse of a predetermined polarity of sumcient amplitude to drivethe core from saturation in one magnetic polarity into saturation in theopposite magnetic polarity. An output winding would then produce anoutput pulse if the core were driven from saturation of one polarity tosaturation of the other polarity, but would produce no output pulse ifthe core were previously saturated in the opposite polarity by thestored information. Thus, each core could be used to store a binarydigit of information. It has also been previously known that groups ofcores could be oriented and interconnected to produce variouscombinations of storage and transfer systems for computer purposes.

This invention discloses a particular inter-connection of groups ofcores wherein signals may be transferred from one core to another withextreme rapidity and wherein a minimum number of cores and controlcircuits are required for the storage of any given number or bits ofinformation. Briefly, the system comprises a plurality of cores, each ofwhich has an input winding, an output winding, and an actuation ortransfer winding positioned thereon. The output winding of one core isconnected to the input winding of another core through circuitryincluding a unidirectional conductor and the actuation coils of all thecores are connected in series with each other to a source of actuationpulses, which preferably comprises a constant current driver, such as avacuum tube pentode amplifier. The circuit connection between the outputwindings and input windings of the different cores contain time delaydevices which delays the output pulse from the preceding core untilafter passage of the actuation pulse through the actuation winding. Thesignal in the delay network then feeds into the input winding and andintroduces the signal from the previous core into the core.

This invention further discloses a particular system for delaying theoutput signal from the output winding until after passage of theactuation pulse. Briefly, this com prises a condenser connected inseries with the undirectional conductor across the output winding of thecore, said condenser being connected in series with a resistor acrossthe input winding of the next core. The condenser must be charged by thesignal available at the output winding of the previous core to a highenough energy level to adequately actuate the input winding of the nextcore when discharged through said winding in series with the resistor.The value of the resistor, in combination with the resistance of theinput winding, is large enough to cause the circuit including the inputwinding, the condenser, and the resistor to have substantial damping,preferably greater than critical damping, whereby oscillations in thiscircuit will not occur. The value of the resistor is large enough toprevent any substantial dis charge of the condenser during the actuationpulse, but small enough to allow sufiicient subsequent current flow latented Eats. 22, l fid to the input winding to eifectively energizesaid winding.

This invention further discloses that the amplitude of pulses into thedelay network and the time duration of the actuation pulses into theactuation windings may be closely controlled to produce reliableoperation of the system by feeding all the actuating windings of thecores in series with each other. Preferably, the actuation windings arefed from an amplifier having a high plate resistance, such a vacuum tubepentode amplifier also sometimes known as a constant current generator.

Referring now to the accompanying drawings:

FIG. 1 illustrates a diagrammatic view of a system embodying thisinvention showing the details of the source of actuation pulses; and

FIG. 2 illustrates a diagrammatic view of a system embodying thisinvention illustrating a particular network useful for interconnectingthe output windings and the input windings of the cores.

Referring now to FIG. 1, there is shown a plurality of magnetic coresillustrated diagrammatically at it). These cores, as shown here, arepreferably toroidal in form and may be made of any desired materialhaving the characteristics of high magnetic retentivity and a relativelyopen hysteresis loop characteristic, preferably approaching that of arectangle. These characteristics are available in cores made fromplastic bonded ferrites or cores made of nickel-iron alloys. Each ofcores 10 has wound thereon a first winding 11, a second winding 1'12,and a third winding 13. The windings ll serve as input windings wherebysignals may be stored in the cores 1%, the windings l2 serve asactuation windings whereby signals stored in the cores 10 may be drivenout there from, and the windings l3 serve as output windings wherebysignals stored in the cores ill may be transferred to other cor-es, orany other desired circuit. As shown here, the windings Ill on the firstcore is connected to a pair of input terminals 14, which may be theoutput of a previous core, or any other desired source of informa ticnpulses. The output windings 13 of the cores are connected throughrectifiers l5 and delay networks 16 to the input windings ill,respectively, of successive adjacent cores. The output of the time delaynetwork 16 fed by the last of the output windings 13 of the cores 10 isshown connected to a set of output terminals 17, which may be connectedto any desired output circuit, or if desired, may be connected back tothe input terminals 14 of the first core winding either directly orthrough any desired number of successive core stages.

The rectifiers 15 may be any desired low impedance rectifier illustrateddiagrammatically as crystal rectifiers. Conventional selenium rectifierswill produce good results, but preferably, germanium rectifiers usinggold bonded contacts are used. If desired, vacuum tubes or gaseousdischarge rectifiers having suitably low drops, could be used, most ofthose available, however, requiring a relatively large number of turnson the windings 11 and 13 to produce sufiiciently high voltages foradequate operation.

The time delay networks 16 may be of any desired type, for example, theymay be conventional lump constant inductance capacitance type networks.indeed, it should be clearly understood that the term time delay meansas used throughout the specification and claims includes all means andmethods of producing a time delay of electrical signals, such as a sonictime delay with transducers, an electronic time delay using vacuum orgaseous discharge devices, magnetic time delays wherein information isstored, for example in cores, then read out therefrom, electrostatictime delays wherein the signal is stored as a charge, for example in acondenser for a period of time, or any other known means of producing atime delay.

The actuation windings 12 are all connected in series,

one end of the series being connected, for example'by a lead 18 throughan inductance 19 to the anode 20 of a vacuum pentode 21, which serves asa source of consum: current actuation pulses for driving the windings 12"such that the coreschan'ge from magnetic saturation of one polarity tomagnetic saturation of the opposite polarity. The suppressor grid 22 andthe cathode 23 of tube 21 are connected t'o'ground. The screen grid 24of tube 21 is connected to a source of positive potentialof, for example+150 volts, while the grid 25 of tube '21 is connected to acurrent-limitingresistor 26 and the seco'ndary winding 27 of a pulsetransformer '28 in series is connected to a source of negative potentialof, for example, '65 volts, which maintain "tube 21 normally c'ut elf.Transformer secondary winding 1.2."1 is shunted by a'resistorfvii' forthe purpose of broadening the frequency response characteristics oftransformer 28 and insuring against any undesired spurious oscillationsfrom being generated in the'grid circuit oftube 27.. The primary winding29 of transformer 23' may be driven from any desired source oftriggering pulses, preferably having substantiallythe same voltage shapeas the desired current wave form to be passed through the windings 712,.The other end of the series of windings 12. from that connected to theinductance 1 is connected to a source of positive potential of," forexample, +200 volts.

- In operation input pulses are applied to the terminals 14, which maybe, for example positive current pulses, the presence of apulse'signifying, for example one information 'bit'and the absence of a pulsesignifying another information bit. The presence otapulse causes thefirst magnetic core 1d 'to'be saturated in 'apredetermined directiondesignated, for example, 'as'a positive direction. If an actuation pulseis applied to the winding 12 after the first core has, been saturated inits'positive direction, said actuating pulse having a polarity such thatit drives the magnetization of the core into its negative saturationregion, a high amplitude pulseappears'at theoutput winding '13. if,however, core has not been saturated in a positive direction indicatingthe absence of a previous positive input pulse to the input winding 11,the previous actuating pulse would have left the core saturated in "anegative polarity, and, hence, the next actuation pulse produces "nooutput at the output windinglE's. The effective delay of the delaynetwork 16 is suiiicientiy long to allow the'actuation pulse toterminate before thesignal introduced therein from the output windingreaches the input winding of the next core, and, therefore-theinformation is preservedduring the period'of the actuation pulses andnot masked out thereby.

Referring now. to HG. 2,-there isshowna particular time delay networkfound to be particularly useful for the network 16 of FIG. 1, There areshown cores with windings similar to those shown-in FIG. 1 anddesignated by similar numerals. The box 32 labeled pulse driver may-besimilar to the'elementslfl through 31 of FIG. 1 and'drives,the'ac'tuation' cores 12 inseries in the same manner.The'dlelay'networlr' rs of FIG; 1 is shown specifically in FIG. '2 as acondenser 33 connected in series with the re'ctifierlS a'crossftheoutput winding 13. .A resistor 34 is also connected in series with theinput winding 11 a'cross'the condenser 33. Resistor 34- is adjusted tocritically damp the resonant circuit corn rising'the condenser 33 andthe leakage rcactance of it input winding 11, such that when the outputpulse from the output winding 13 feeds into the condenser 33 and fromthere feeds into the input winding 11, through the resistor 34,oscillations will not occur. Preferably, the value of resistor 34 issufficiently high to somewhat overdamp this resonant circuit. Underthese conditions, the bulk of an output signal of an output winding 13is stored in a condenser '33 until the actuation pulse applied totheactuation windings lzhas ended, and then condenser 33'dischargesthrough the inputwindingll of theneirt core.

While discharge of the condenser 33 begins the flow of current throughthe resistor 34 and the input Winding 1-1 while the actuation pulse ispresent, the bulk of the energy fed into the condenser 33 remains thereuntil after cessation of the actuation pulse. With such a circuit,information may he stepped along from one core to the next at a rate inexcess of 20 kilocyclcs per second. The junctions between the rectifiersl5 and the condenser 33 may be used for output pulses, as indicated byterminals 35, which may be connected to other registers for computerpurposes, or the terminals 35 maybe used to set up or introduce pulseinformation into the cores. In this event, the opposite sides of thecondenser 33 are normally grounded, as indicated.

Sincejthe load presented to the actuation pulses applied to the windingsl2'v'aris greatly, dependent on whether an information pulse is storedin a particular core, or whether the "core has nothing stored therein,it is desirable, for reliable operation, that the cores 12 allbeko'hnbbted in series from "the same driver. Under these conditions,the magnetizing current in all the windings is equal at 'all times andthedura'tion of the current in allw'indin'gs is equal at all tin'ies.If, for eitample, the windings were fed in parallel from a source ofpulses, there would be a larger current through those windings where 'nop'ulse signals 'were s'tored than through those windings where pulsesignals were stored. The ratio of the current through the windings 'forthese two conditi'onsm'a'y be as great as seven to one, and under theseconditions, substantially no current would pass through the windinghaving the larger impedance, and, hence, an eifective output pulse wouldnot occur. In addition, the'energy content in'the high impedance windingwould be greater, and, accordingly, current would fiow therein followingcessation of the pulse due to the inductive kick thereofgsaid currentflowing in the reverse direc tion through any windings having lowi'rnpedanccs due to the presence of zero pulse positions, this, in turn,producing an undesirable oscillatory condition in the actuationcii'cuits'which would-seriously affect the-opera tionof the storagesystern,'if, indeed, operation at all possible. The 'series connectionof the actuation winding's Ilisp'artioular'ly useful inthecase wheresuccessive cores are actuat'edby thesame'aetuation signals. Under theseconditions where theoutput 'pulse is stored in a delay networkbetweensuccessive cores, the tiiningof the actuation pulses, with respect tothe storage time, is'critical' for optimum operation of the-system,since, if'the "actuation-pulse is too long, the pulse-in the delaynetworkis'a'pplied :to the input winding before "termination of theactuation pulse a'ndis lost. 'On the other handif the 'actuat'ionpuls'eis'too' small, insufiicie'nt time is"allowedto drive the core completely=into saturation inthe oppositedirecti'on an'dthe output pulse to'thedelay network'is too low to 'pr'od'uce sdfiiciritnergy to magnetize thenext core completely-into thedsired positive saturation.

This completes the description of thepafticular embodiments of theinvention illustratedher'ein. HoWever, manyrno'dificationsthereof'willbe apparent to persons skilled in the art without departingfrom the spiritand scopeof this invention. For eXarnplq'ya'rious -f0rmsof pulse drivers could be used using gaseous'dis'chargedevices,"mag'ne'tic amplifiers, or other-devices in place of the vacuumtube amplifier shown. The cores need notnec'es- 'sarily be toroidal inshape, and'rnay'be of any desired material having the requisitecharacteristics, and any niunb'er of windings can be used -on*the'coresfor various input or output signals in addition to those'alreadyfim-'pre sfsed 'on the cores Accordingly, it is desired that this inventionbe'not limited to the particular" details, of the embodimentsillustrated herein, except *as' defined by the appended claims,

What is claimed is '1. A magnetic control system com risin ai'pluralityof magnetic cores the magnetic material of high retentivity, first,second, and third electrical windings on each of said cores, criticallydamped electrical circuitry including a delay Iunit having a condenserand a damping resistor for feeding signals within a fixed time cyclefrom said third winding of one of said cores to said first winding ofanother of said cores, unidirectional current means connected betweensaid third winding and said condenser, and a single series-connectedelectrical circuit for simultaneously feeding said second winding ofeach of said cores in series with each other from a substantiallyconstant current source of actuating signals to cause the same currentto flow through all of said second windings.

2. A magnetic control system comprising a plurality of magnetic cores ofmagnetic material of high retentivity characteristics, first, second,and third electrical windings on each of said cores, critically dampedelectrical circuitry including a series connected resistor-condenserdelay unit for feeding signals within a fixed time cycle from said thirdwinding of one of said cores to said first winding of another of saidcores, unidirectional current means connected in series with said thirdWinding and the condenser of said delay unit to prevent current flowback into said third winding, and a single series-connected electricalcircuit for simultaneously feeding said second winding of each of saidcores in series with each other from the plate circuit of a pentodevacuum tube amplifier, to cause the same current to flow through all ofsaid second windings.

3. A magnetic control system comprising a plurality of magnetic coresthe magnetic material of high retentivity, first, second, and thirdelectrical windings on each of said cores, electrical circuitconnections between said first winding on one of said cores and saidthird winding on another of said cores, said connections including meansfor transmitting an electrical signal from said first winding to saidthird winding within a fixed time cycle only when the flux directionwithin the core of said winding changes from a predetermined fluxdirection to the other flux direction in response to an actuating signalapplied to said second windings, said transmitted signal causingmagnetic flux Within the core of said third winding to be oriented insaid predetermined flux direction, said connections further including asingle condenser and resistor for providing a critically damped circuitin connection with said third winding including a time delay betweensaid actuating signal and said transmitted signal, unidirectionalcurrent means interposed in advance of said time delay means forcooperating with said time delay means to prevent oscillation and thetransmission of and electrical signal from said third windings to saidfirst windings, and means for simultaneously feeding said secondwindings of each of said cores connected in a single series circuit witheach other from a single source of actuating signals, to cause the samecurrent to flow through all of said second windings.

4. A magnetic control system comprising a plurality of magnetic coresthe magnetic material of high retentivity, electrical input, output andtransfer windings on each of said cores, a damped electrical circuitincluding a delay unit provided with a critical damping resistor,unidirectional current means connected between said output winding andsaid delay unit on each of said cores, the output of said delay unitconnected to a corresponding input winding on said cores, saidconnections including means for transmitting an electrical signal fromsaid output winding through said critical damping resistor to saidcorresponding input winding within a fixed time cycle only when the fluxdirection Within the core of said one winding changes in a predetermineddirection, constant current means for changing the flux direction withinthe core of said one winding, comprising a single series-connectedwinding on each of said cores, and means for causing the same current toflow through all of said last-named windings.

5. A magnetic control system comprising a plurality of magnetic coresthe magnetic material of high retentivity, electrical windings on eachof said cores, one set of corresponding windings thereof being connectedin a single series circuit with each other to a source of electricalactuating signals, delay circuits comprising seriesconnected resistivemeans adapted to critically damp oscillations and shunt-connectedcapacitive means connected between the output windings of each core andthe input windings of the adjacent cores to form with said latterwindings a critically damped intercore circuit, and unidirectionalimpedance means connected in advance of each of said delay circuits andafter each output winding to allow voltages of only one predeterminedpolarity induced in the winding of one core to produce signal current inthe winding of the succeeding core and to prevent voltages induced inthe winding of the succeeding core from producing signal current in theassociated winding of the preceding core.

6. A magnetic control system comprising a plurality of magnetic coresthe magnetic material of high retentivity having substantiallyrectangular hysteresis characteristics, an input winding and an outputwinding on each of said cores, means for connecting actuating windingson each of said cores in a single series circuit to a source ofelectrical current pulses to be scaled, means connecting each of saidinput windings to the output windings of a different one of said coresfrom the core of that input winding, said input and output windingsthereby being connected in closed cascading relation through said cores,each of said connecting means including a delay circuit having aresistor and a condenser adapted to critically damp the leakage of saidcorresponding input winding, and a unidirectional impedance interposedbetween each output winding and its delay circuit, to prevent flow-backof energy into said output winding.

References Cited in the file of this patent UNITED STATES PATENTS2,652,501 Wilson Sept. 15, 1953 2,654,080 Browne Sept. 29, 19532,708,722 An Wang May 15, 1955 2,825,890 Ridler Mar. 4, 1958

1. A MAGNETIC CONTROL SYSTEM COMPRISING A PLURALITY OF MAGNETIC CORESTHE MAGNETIC MATERIAL OF HIGH RETENTIVITY, FIRST, SECOND, AND THIRDELECTRICAL WINDINGS ON EACH OF SAID CORES, CRITICALLY DAMPED ELECTRICALCIRCUITRY INCLUDING A DELAY UNIT HAVING A CONDENSER AND A DAMPINGRESISTOR FOR FEEDING SIGNALS WITHIN A FIXED TIME CYCLE FROM SAID THIRDWINDING OF ONE OF SAID CORES TO SAID FIRST WINDING OF ANOTHER OF SAIDCORES, UNIDIRECTIONAL CURRENT MEANS CONNECTED BETWEEN SAID THIRD WINDINGAND SAID CONDENSER, AND A SINGLE SERIES-CONNECTED ELECTRICAL CIRCUIT FORSIMULTANEOUSLY FEEDING SAID SECOND WINDING OF EACH OF SAID CORES INSERIES WITH EACH OTHER FROM A SUBSTANTIALLY CONSTANT CURRENT SOURCE OFACTUATING SIGNALS TO CAUSE THE SAME CURRENT TO FLOW THROUGH ALL OF SAIDSECOND WINDINGS.